"Porque todos respiramos lo mismo" is a mass media campaign to promote smoke-free places (SFP). The development stages were: strategic planning; formative research; message development; media plan; and impact evaluation. Development involved formation of a coalition of key actors in various sectors. The target population was smokers and nonsmokers, with the aim of changing social norms around SFP. Nonsmokers were targeted because they comprised the majority and were most likely to appreciate the benefits of SFPs. Campaign materials were aired on television, radio, print and on billboards. One key limitation was the lack of evidence for previous campaigns, which increased the importance of formative research and of including a rigorous evaluation for this one. The campaign evaluation indicates a significant impact, which suggests that future campaigns use similar strategies in their development.